The present invention relates to deposition processes and components used in semiconductor device fabrication chambers, including recyclable process kit components.
The formation of semiconductor devices often includes depositing various layers onto a substrate using methods such as physical vapor deposition (sputtering) and chemical vapor deposition. Such methods tend to form a layer of deposition material not only on the substrate, but also on other exposed surfaces in the processing chamber. Particles of the material deposited on the other exposed surfaces in the processing chamber may flake off during various processing cycles such as heating, cooling, pressure changes, etc., and contaminate the device being formed. In order to reduce contamination, chamber surfaces which are exposed to deposition material may be periodically cleaned or replaced.
One technique for cleaning and replacement includes the use of recyclable process kits including chamber components that can be removed from the chamber, cleaned of deposition material, and then reused in the chamber. By using recyclable components, the chamber down time is minimized because many of the components can be quickly replaced with a second set of clean components and the first set of components can then be cleaned outside of the chamber. While the first set of components is being cleaned, the chamber is available for processing. Process kits may include one or more components, depending on factors such as the type of chamber, the wafer support pedestal, the type of deposition being carried out, and the process being carried out in the chamber. Certain known deposition chambers, for example, may utilize a variety of pedestals, including those that operate in conjunction with a clamp ring that holds a wafer to the pedestal, and those that operate without a clamp ring and leave the entire surface of the wafer available for deposition. Some pedestals also utilize electrostatic forces to attract the wafer to the pedestal surface. Chamber components which may be removed and recycled include, but are not limited to, shields, coils, pedestals, shutters, collimators, deposition rings, cover rings, clamp rings, and showerheads as known in the art.
The recyclable chamber components may be cleaned using a variety of chemical and physical methods known in the art. One chemical method includes submersing the component in a chemical solution that chemically etches the deposited material from the component. One such physical method is bead blasting, which physically removes deposited material from the component. Due to the desirability of removing all or nearly all of the deposited material on the process kit component, a quantity of the base material the component is formed from (for example, titanium) is often also removed during the cleaning operation, thus shortening the life of the component. After a number of cycles of deposition followed by cleaning, a sufficient quantity of base material may be removed such that the component no longer meets the acceptable tolerances to properly perform its intended function. In addition, base metal removal may result in the surface of the component having an undesirable level of surface roughness, which can lead to problems such as deposition material flaking off the component while in the processing chamber and contaminating the workpiece.
Metrology methods may be used to determine whether a component is out of tolerance. However, such methods are time consuming. Methods for determining the surface roughness are also time consuming and add costs to the overall process. Because the amount of material removed during a cleaning process can be difficult to determine, a recommended number of cleanings is sometimes specified by the manufacturer for recyclable components, in order to ensure that the components will remain in tolerance. When the recommended number of cleanings is reached, the component is disposed of. Depending on the actual amount of base material removed during the cleaning cycles, the component may still be useable despite reaching the recommended number of cleanings. As a result, employing a recommended number of cleanings approach may result in recyclable components being discarded prematurely.
Certain embodiments of the present invention relate to a device for use in a deposition chamber. The device comprises a recyclable process kit component including a base metal and a protective layer formed on the base metal. The protective layer comprises a material having a different composition than the base metal. In one aspect of certain embodiments, the base metal is titanium. In another aspect of certain embodiments, the protective layer is a nitride layer having a thickness of no greater than {fraction (10/1000)} inch.
Embodiments also include an apparatus including a base metal shaped in the form of a recyclable process kit component and an etch stop layer on the base metal. The etch stop layer comprises a material having different etching properties than the base metal.
Other embodiments relate to an apparatus for sputtering material onto a workpiece, the apparatus including a vacuum chamber and a target disposed in the vacuum chamber, the target comprising a material to be deposited onto the workpiece. The apparatus also includes a holder (commonly referred to as a pedestal or chuck) for the workpiece and at least one recyclable process kit component positioned to accumulate material sputtered from the target. The process kit component includes a base metal layer including titanium and an outer layer including nitrogen. In one aspect of certain embodiments, the process kit component is selected from the group consisting of a shield, pedestal, shutter, coil, collimator, deposition ring, cover ring, and clamp ring.
Other embodiments relate to a method including performing a plurality of deposition operations in a process chamber so that material is deposited on a recyclable component. The recyclable component includes a base metal and an etch resistant layer on the base metal. The method also includes removing the recyclable component from the process chamber and etching the deposited material from the recyclable component. The etching is stopped when the etch resistant layer is reached.
Still other embodiments relate to a method for forming a process kit component outside of a semiconductor processing chamber, including forming a body into the shape of a process kit component and forming a nitride layer to a depth in the body. In one aspect of certain embodiments, forming a body into the shape of a process kit component includes performing a first machining operation on a metal body comprising titanium to form a shape close to that of a desired process kit component, performing a first heat treating operation on the body to relieve stresses generated in the body during the first machining, and performing a second machining operation on the body to form the body into a shape closer to that of the desired process kit component. Certain embodiments may also include performing a second heat treating operation on the body after the second machining operation.